21009+3900
- Unique Name: 21009+3900SEI1365
- RA: 21 00 48.52
- Dec: +38 59 44.0
- Discoverer: SEI
- Discoverer Number: 1365
- Components:
- First year: 1895
- Last year: 2011
- Observations: 6
- First position angle: 270
- Last position angle: 263
- First separation: 17.4
- Last separation: 18.3
- Mag first component: 11.4
- Mag second component: 11.9
- Spectral type:
- Primary proper motion RA: 7
- Primary proper motion DEC: 15
- Secondary proper motion RA: -1
- Secondary proper motion DEC: -3
- Durchmusterung:
- Notes: